The invention is directed to integral temperature measurement in electrical machines, transformers and energy conversion systems by interpreting the temperature dependency of the propagation conditions of sound or ultrasound in gases. Energy conversion systems include gas turbines, internal combustion motors, heating systems, etc.
The winding temperature is a critical operating characteristic of electrical machines. A point temperature value is of less interest than an integral, mean temperature indication over the entire winding. A continuous, automatic monitoring of this characteristic would represent a decisive advance in the operating reliability of electrical machines.
Until now, the integral temperature of the stator winding was obtained by a resistance measurement of the copper windings. The separation of the power circuit and the test circuit, however, results in a considerably complex circuit so that a mass-produced integration of this measuring method in standard machines is not economically feasable. No measuring methods are known for the integral temperature measurement of the rotor winding.